JSFiddle - React, Tailwind, and code Playground

HTML

<article class="infobox">
    <section id="allgemeines">
        <h2><a href="#allgemeines">Allgemeines</a></h2>
        <p>Hier stehen ganz allgemeine Informationen.</p>
    </section>
    <section id="funktionen">
        <h2><a href="#funktionen">Funktionen</a></h2>
        <p>Hier stehen Informationen zu den Funktionen</p>
    </section>
    <section id="preise">
        <h2><a href="#preise">Preise</a></h2>
        <p>Hier stehen Informationen zu den Preisen.</p>
    </section>
</article>

CSS

article.infobox section {
    position: absolute;
    display: block;
    width: 400px;
    height: 200px;
    top: 100px;
    background-color: #c5d2de;
}

article.infobox section h2 {
    position: absolute;
    left: 0;
    top: -30px;
    width: 124px;
    height: 29px;
    font-family: Verdana;
    font-size: 15px;
    margin: 0;
    background-color: #194b7d;
    border-radius: 15px 15px 0 0;
    border: solid #ffffff;
    border-width: 1px 1px 0 0;
    z-index: 1;
}

article.infobox section:nth-child(2) h2 {
    left: 120px;
    z-index: 0;
}

article.infobox section:nth-child(3) h2 {
    left: 240px;
    z-index: -1;
}

article.infobox section h2 a {
    display: block;
    margin: 5px 0 0 0;
    text-align: center;
    text-decoration: none;
    color: #c5d2de;
}

article.infobox section:target, article.infobox section:target h2 {
    color: #000000;
    background-color: #c5d2de;
    z-index: 1;
}

article.infobox section:target h2 a {
    color: #194b7d;
}

article.infobox section p {
    font-family: Verdana;
    font-size: 15px;
    margin: 10px 10px 0 10px;
}